Handling quizzes in Rails

I am currently trying to create a logic on my Site in Ruby on Rails. The Users should have the ability to answer a question via multiple checkboxes or text input. First attempts have failed when using check_box_tag. In the controller, I am checking

if @@user_solution.to_s == @@solution.to_s

at submitting and if true, the User gets to the next question. I wasn't able to get the solution the user provided via checkbox from the .erb File to the controller (The Question and the answers are in an erb File for each question).